The following abbreviations and terms are herewith defined, at least some of which are referred to within the following description of the present disclosure.
3GPP 3rd-Generation Partnership Project
AGCH Access Grant Channel
ASIC Application Specific Integrated Circuit
BLER Block Error Rate
BLKS Blocks
BSS Base Station Subsystem
BSSGP Base Station Subsystem General Packet Radio Service Protocol
CC Coverage Class
CN Core Network
DRX Discontinuous Receive Cycle
EC-GSM Extended Coverage Global System for Mobile Communications
EC-PCH Extended Coverage Paging Channel
eDRX Extended Discontinuous Receive
eNB Evolved Node B
DL Downlink
DSP Digital Signal Processor
EDGE Enhanced Data rates for GSM Evolution
EGPRS Enhanced General Packet Radio Service
FN Frame Number
GSM Global System for Mobile Communications
GERAN GSM/EDGE Radio Access Network
GPRS General Packet Radio Service
GPS Global Positioning System
HARQ Hybrid Automatic Repeat Request
IMSI International Mobile Subscriber Identity
IoT Internet of Things
LLC Link Layer Control
LTE Long-Term Evolution
MCS Modulation and Coding Scheme
MF Multiframe
MFRM Multiframe
MFRMS Multiframes
MME Mobility Management Entity
MS Mobile Station
MTC Machine Type Communications
NB Node B
N-PDU Network Protocol Data Unit
PCH Paging Channel
PDN Packet Data Network
PDTCH Packet Data Traffic Channel
PDU Protocol Data Unit
P-TMSI Packet Temporary Mobile Subscriber Identity
RACH Random Access Channel
RAN Radio Access Network
RAT Radio Access Technology
RAU Routing Area Update
SGSN Serving GPRS Support Node
TDMA Time Division Multiple Access
TLLI Temporary Logic Link Identifier
TS Technical Specifications
UE User Equipment
uPoD device Study of Power saving for MTC Devices
WCDMA Wideband Code Division Multiple Access
WiMAX Worldwide Interoperability for Microwave Access
Coverage Class (CC): At any point in time a wireless device belongs to a specific uplink/downlink coverage class that corresponds to either the legacy radio interface performance attributes that serve as the reference coverage for legacy cell planning (e.g., a Block Error Rate of 10% after a single radio block transmission on the PDTCH) or a range of radio interface performance attributes degraded compared to the reference coverage (e.g., up to 20 dB lower performance than that of the reference coverage). Coverage class determines the total number of blind transmissions to be used when transmitting/receiving radio blocks. An uplink/downlink coverage class applicable at any point in time can differ between different logical channels. Upon initiating a system access a wireless device determines the uplink/downlink coverage class applicable to the RACH/AGCH based on estimating the number of blind transmissions of a radio block needed by the BSS (radio access network node) receiver/wireless device receiver to experience a BLER (block error rate) of approximately 10%. The BSS determines the uplink/downlink coverage class to be used by a wireless device on the assigned packet channel resources based on estimating the number of blind transmissions of a radio block needed to satisfy a target BLER and considering the number of HARQ retransmissions (of a radio block) that will, on average, be needed for successful reception of a radio block using that target BLER. Note: a wireless device operating with radio interface performance attributes corresponding to the reference coverage (normal coverage) is considered to be in the best coverage class (i.e., coverage class 1) and therefore does not make any additional blind transmissions subsequent to an initial blind transmission. In this case, the wireless device may be referred to as a normal coverage wireless device. In contrast, a wireless device operating with radio interface performance attributes corresponding to an extended coverage (i.e., coverage class greater than 1) makes multiple blind transmissions. In this case, the wireless device may be referred to as an extended coverage wireless device. Multiple blind transmissions corresponds to the case where N instances of a radio block are transmitted consecutively using the applicable radio resources (e.g., the paging channel) without any attempt by the transmitting end to determine if the receiving end is able to successfully recover the radio block prior to all N transmissions. The transmitting end does this in attempt to help the receiving end realize a target BLER performance (e.g., target BLER≤10% for the paging channel).eDRX cycle: eDiscontinuous reception (eDRX) is a process of a wireless device disabling its ability to receive when it does not expect to receive incoming messages and enabling its ability to receive during a period of reachability when it anticipates the possibility of message reception. For eDRX to operate, the network coordinates with the wireless device regarding when instances of reachability are to occur. The wireless device will therefore wake up and enable message reception only during pre-scheduled periods of reachability. This process reduces the power consumption which extends the battery life of the wireless device and is sometimes called (deep) sleep mode.Extended Coverage: The general principle of extended coverage is that of using blind transmissions for the control channels and for the data channels to realize a target block error rate performance (BLER) for the channel of interest. In addition, for the data channels the use of blind transmissions assuming MCS-1 (i.e., the lowest modulation and coding scheme (MCS) supported in EGPRS today) is combined with HARQ retransmissions to realize the needed level of data transmission performance. Support for extended coverage is realized by defining different coverage classes. A different number of blind transmissions are associated with each of the coverage classes wherein extended coverage is associated with coverage classes for which multiple blind transmissions are needed (i.e., a single blind transmission is considered as the reference coverage). The number of total blind transmissions for a given coverage class can differ between different logical channels.MTC device: A MTC device is a type of device where support for human interaction with the device is typically not required and data transmissions from or to the device are expected to be rather short (e.g., a maximum of a few hundred octets). MTC devices supporting a minimum functionality can be expected to only operate using normal cell contours and as such do not support the concept of extended coverage whereas MTC devices with enhanced capabilities may support extended coverage.uPoD device: A uPoD device is similar to a MTC device except it also supports the mandatory use of a power saving state known as eDRX or Power Saving Mode (PSM) which allows for substantial battery savings to be realized in packet idle mode.Nominal Paging Group: The specific set of EC-PCH blocks a device monitors once per eDRX cycle. The device determines this specific set of EC-PCH blocks using an algorithm that takes into account its IMSI, its eDRX cycle length and its downlink coverage class.
The need to support MTC devices using cellular technologies is increasing because the cellular technologies represent existing (and therefore convenient) deployments of service areas in which MTC devices can operate. As a result, more and more MTC devices are being deployed in wireless communication networks. One challenge facing the deployment of MTC devices in wireless communication networks is that the MTC devices will typically not have access to external power and, as such, will need to make use of batteries with target lifetimes in the area of years. To help realize such battery lifetimes, the use of extended discontinuous receive (eDRX) functionality may be seen as necessary, where eDRX cycle lengths will be in the area of minutes to hours (i.e., a MTC device will support one paging occasion per eDRX cycle), compared to legacy operation, where discontinuous receive (DRX) cycle lengths are in the area of a few seconds. The possibility of MTC device mobility also needs to be taken into account including the issue of how the reachability of a MTC device (e.g., using the MTC device's paging occasion) will be impacted as a result of the possible mobility of the MTC device.
The paging occasion (nominal paging group) used by a wireless device (e.g., MS, MTC device) on the radio interface is currently determined, at least in part, by the radio frame number. This is described in multiple 3GPP TSs such as, for example, 3GPP TS 36.331 V.12.5.0 (dated 2015 Mar. 27), 3GPP TS 45.002 V.12.4.0 (dated 2015 Mar. 21), and 3GPP TS 25.304 V.12.5.0 (dated 2015 Mar. 23) (the contents of these documents are incorporated herein by reference for all purposes). A problem with this technique is that the cycle of radio frame numbers in different cells will appear on the radio interface in an uncoordinated manner in the time domain (i.e., when paging a wireless device in a given paging area comprising multiple cells, the corresponding paging message will be sent on the radio interface to different cells at different points in time).
With this lack of time coordination, the spread between paging occasions for the same wireless device in different cells can be up to the maximum extended DRX cycle length, since the same radio frame number associated with the start of a nominal paging group can occur at different times in different cells. Therefore, the lack of time coordinated cells has some drawbacks when considered within the context of eDRX. Some of these drawbacks are as follows:                Drawback 1: A wireless device might be unreachable for paging, as the wireless device might miss its paging opportunities (in different cells) as a result of the wireless device moving between cells.        Drawback 2: A wireless device might receive and respond to the same paging message multiple times (in different cells) as a result of the wireless device moving between cells.        Drawback 3: Temporary identifiers (e.g., Packet Temporary Mobile Subscriber Identity (P-TMSI)) included in the paging message might become invalid if the paging messages are buffered in the radio access network (RAN) node for extended time periods (e.g., P-TMSI re-allocation could occur while a page with that P-TMSI is buffered). If this happens, then if the buffered page is eventually sent, this could then lead to either a paging failure (e.g., the intended wireless device is not paged) or, at least, a waste of paging bandwidth. To mitigate these problems, additional signaling and complexity would need to be introduced.        
This lack of time coordinated cells and the resulting paging problem is addressed by the present disclosure.